Package for electrophoresis gels

ABSTRACT

A packaging arrangement is disclosed for protecting an electrophoresis gel from damage during shipment and storage. The package arrangement includes first and second sheets that are sealed about their respective edges to form an enclosed cavity. The cavity is at least partially evacuated of air. An electrophoresis gel is located within the cavity. A support sheet may be disposed between the electrophoresis gel and the package to facilitate removal of the gel and to further stiffen the package. In one embodiment of the invention, a plurality of electrophoresis gels are disposed within the cavity. Each gel is preferably separated from adjacent gels by a spacer. In another embodiment of the invention, the gel is disposed within a tray which, in turn, is located within the cavity.

RELATED APPLICATIONS

This application is a continuation-in-part of patent application Ser.No. 09/177,469, entitled “Vacuum Package for Electrophoresis Gel”, filedOct. 23, 1998, now U.S. Pat. No. 6,090,255 which is incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to packaging for electrophoresis gels and,more particularly, to an improved vacuum sealed package combination forcontaining and protecting electrophoresis gels during storage, handlingand shipment.

BACKGROUND OF THE INVENTION

Most biological macromolecules are electrically charged such that, whensubjected to an electrical field, they begin to move, This phenomenon isthe basis behind an electrophoresis process wherein a prescribedelectrical current is generated adjacent to a collection ofmacromolecules to produce movement of the macromolecules through asolvent in a particular direction. Since different macromolecules varyin molecular size, weight and charge, it is possible to use anelectrophoresis process to distinguish between different macromoleculesbased on their respective rates of movement through the solvent.Electrophoresis can also be used for other types of macromoleculeanalysis, such as detecting amino acid changes, nucleic acid sequencingand protein analysis.

One medium that has been used for over thirty years as the carrier forthe macromolecules in an electrophoresis process is a gel. Two of themost popular types of gels are agarose and polyacrylamide gels. Anelectrophoresis gel is typically planar in shape and includes a seriesof spaced apart wells. The wells are designed to receive the biologicalsample being tested. In the past, it was customary for the laboratorythat was conducting the testing to cast their own gels by hand. It soonbecame apparent, however, particularly as electrophoresis testing of DNAincreased, that it is more convenient and more precise to use precastgel slabs made to uniform composition, size and well configurationstandards.

Conventional gels are made from various materials depending on theirintended use. One widely used gel material for DNA electrophoresis isagarose. This gel is a sugar based gel that is highly flimsy and subjectto tearing and deformation if not handled carefully. Tearing or crackingis especially prone between the wells where the least amount of materialis present. Deformation or tearing of the gel can potentially produceinaccuracies during testing. To complicate matters further, the materialproperties of the gel make detecting hairline cracks very difficult.Hence, proper packaging of the gels is extremely important when shippingor storing the gels.

Several packaging arrangements have been developed in recent years toprotect electrophoresis gels during shipment. U.S. Pat. No. 5,443,704discloses one packaging arrangement for protecting the gels. Thispackaging arrangement includes a plastic tub within which the gel isplaced. A foil-lined cover is adhered to the top of the tub to retainmoisture inside the package. It was subsequently determined that the tubalone did not provide sufficient protection for the gel. Fillermaterials had to be added to the box to provide adequate protection fromdamage. As a result, this type of packaging arrangement is generallyvery expensive to produce.

Another prior packaging arrangement for shipping gels includes a pouchformed from foil material that is sealed along each edge. In order toprotect the gel, a separate sheet of material is folded over the gel toseparate it from the foil. A deficiency with this packaging arrangementis that the package does not adequately protect the gel from damage suchas edge deformation and well breakage.

U.S. Pat. No. 5,837,288 discloses one particular type of pouch whereinthe pouch is almost completely evacuated of air prior to sealing,resulting in a reduced atmospheric environment (i.e., less than 10% ofatmospheric air pressure). Spacers are used on the sides of the gel toprevent the package walls from crushing the sides of the gels.

Co-pending patent application Ser. No. 09/177,469, entitled “VacuumPackage for Electrophoresis Gel”, filed Oct. 23, 1998, discloses analternate package configuration which, in one embodiment, uses a supportsheet in combination with a sealed, at least partially evacuatedinterior to restrain the gel within the package for preventing geldamage during storage and shipping.

A need exists for an improved packaging arrangement which is inexpensiveto manufacture and which adequately protects a gel or series of gelsfrom damage during shipment, handling or while stored.

SUMMARY OF THE INVENTION

An object of the invention is to provide a package for anelectrophoresis gel which includes sufficient rigidity to prevent damageto the gel and minimize movement of the gel within the package. Thewells in the gel make it particularly susceptible to damage and breakageduring shipment.

Another object of the invention is to provide a package for anelectrophoresis gel which, in one embodiment, includes a support traythat functions as part of the packaging during shipment and can besubsequently used to hold the gel during an electrophoresis process.

These and other objects and advantages of the invention are provided bythe packaging arrangement according to the present invention. Thepackaging arrangement includes first and second sheets that are sealedalong their respective edges to form an enclosed cavity. In oneembodiment, the cavity is at least partially evacuated of air prior toor after sealing. At least one electrophoresis gel is disposed withinthe evacuated cavity. The partial evacuation of air from the cavitycauses the top and bottom sheets to conform to the gel, therebyrestraining it from movement within the package.

In one embodiment of the invention, a tray is incorporated into thepackage. The gel is located within the tray which, in turn, is locatedbetween the top and bottom sheets. The tray includes a base and at leasttwo side walls which extend upward along the longitudinal sides of thegel. The combination of the low pressure environment in the package andthe tray produces a rigid packaging configuration that minimizes motionof the electrophoresis gel contained therein.

The foregoing and other features and advantages of the present inventionwill become more apparent in light of the following detailed descriptionof the preferred embodiments thereof, as illustrated in the accompanyingfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, the drawings show a formof the invention which is presently preferred. However, it should beunderstood that this invention is not limited to the precisearrangements and instrumentalities shown in the drawings.

FIG. 1 is a plan view of one embodiment of an electrophoresis gelpackage according to the present invention.

FIG. 2 is a partially broken away isometric view of the electrophoresisgel package, illustrating an electrophoresis gel contained within apartially evacuated cavity.

FIG. 3 is a partially broken away isometric view of another embodimentthe electrophoresis gel package according to the present invention,illustrating a plurality of electrophoresis gels contained within acavity.

FIG. 4 is a cross-sectional view of the electrophoresis gel package ofFIG. 3 illustrating the interleaving of spacer sheets between adjacentgels.

FIG. 5 is a partially broken away isometric view of an alternateembodiment of the electrophoresis gel package, illustrating anelectrophoresis gel contained within a tray in a partially evacuatedcavity.

FIG. 6A is a cross-sectional view of the electrophoresis gel package ofFIG. 5.

FIG. 6B is a cross-sectional view of the electrophoresis gel package ofFIG. 5 that includes a tray with short side walls.

FIG. 7A is a cross-sectional view of one embodiment of the package withmultiple gels interleaved by spacers.

FIG. 7B is a cross-sectional view of another embodiment of the packagewith multiple gels, each gel contained within an associated tray.

DETAILED DESCRIPTION OF THE EMBODIMENTS

While the invention will be described in connection with one or morepreferred embodiments, it will be understood that it is not intended tolimit the invention to those embodiments. On the contrary, it isintended that the invention cover all alternatives, modifications andequivalents as may be included within its spirit and scope as defined bythe appended claims.

Referring now to the drawings, wherein like reference numeralsillustrate corresponding or similar elements throughout the severalviews, FIGS. 1 and 2 illustrate one embodiment of an electrophoresispackage 10 according to the present invention. The package 10 is formedfrom two overlapping sheets 12, 14 that are sealed 16 along their edgesto form an enclosed cavity 18. The cavity 18 is designed to contain atleast one precast electrophoresis gel 20. One preferred gel 20 for usein the present invention is an agarose gel, such as 1% SeaKem® LE, soldby BioWhittaker Corporation, Rockland, Me.

In order to prevent the gel from moving during shipment, the package 10is vacuum sealed 16 along its edges so that the sheets 12, 14substantially conform to the shape of the gel 20. That is, the cavity 18within the package 10 is preferably at least partially evacuated of air.Removal of air from within the package 10 stiffens the sheets 12, 14,thereby increasing the package's strength to better support the gel.

Most conventional sealed packages are not evacuated prior to sealing. Assuch, the residual air contained within the package results in the upperand lower sheets of the package essentially functioning independent fromone another, i.e., they do no support one another. The independentmovement of the sheets reduces the package's stiffness and allowing itto be easily flexed. The relative ease with which non-evacuated pouchescan be flexed increases the chance that the malleable gel containedwithin the package will become damaged.

Additionally, the air trapped within a conventional package produces aninterior volume which is considerably larger than the gel. Accordingly,the gel is generally free to move within the package. Gels areinherently slippery and some gels actually exude moisture, making themeven more prone to sliding within the package. Since the gel is verysoft and pliable, movement during shipment or storage increases thelikelihood of damage to the gel.

The evacuated package design according to the present invention reducesdamage to the gel 20 by stiffening the packaging and reducing themobility of the gel. The vacuum packing/sealing of the packagingeliminates at least a partial amount of the residual air containedwithin the cavity 18 of the package 10 after formation. Preferablybetween about 1% to about 89% of the air within the package 20 isremoved prior to sealing which causes the sheets to conform to the shapeof the gel without crushing the gel. As a result, the upper and lowersheets 12, 14 overlap one another adjacent to the edges of the gel 20and, thus, effectively function as a substantially unitary structure.

Furthermore, the drawing of the upper and lower sheets 12, 14 of thepackage 10 against or in close proximity to the top surface of the gel20 prevents the gel 20 from moving within the package 10 by reducing theinterior volume of the cavity 18 after the gel 20 is inserted into thepackage 10.

The sheets 12, 14 of the package 10 are each made from at least one and,more preferably, several constituent layers. In one embodiment, thelayers form a laminate having a thickness of less than approximately 3.0mil. More preferably, the thickness is about 2.5 mil. In one exemplaryembodiment, each sheet 12, 14 includes a metallized outer layer, anintermediate layer and an inner layer. The layers are preferably adheredto one another with a suitable adhesive. Although the followingdiscussion refers to the upper and lower sheets as being similarlyconfigured, they need not be so. For example, the lower sheet 14 can beselected with a different thickness and/or material than the upper sheet12. Those skilled in the art would readily be capable of making suchmodifications in light of the teachings provided herein.

One problem associated with agarose type gels, such as 1% SeaKem LE, isthat they can deteriorate from loss of moisture when exposed to certainenvironmental conditions. Hence, it is desirable to protect the gel 20from moisture loss by forming the package 10 from material that providesa suitable moisture barrier. In one embodiment of the invention, thepackage 10 is formed from sheet materials with a moisture vaportransmission rate (MVTR) of less than approximately 0.02 grams in 100square inches over a 24 hour period. This preferred moisture vaportransmission rate allows the gel to remain viable for a 12 month shelflife. The moisture transmission rate is determined by measuring theamount of vapor loss through a 100 in² piece of the packaging materialover a 24 hour period of time while exposed to a temperature of 100° F.This test for determining moisture vapor transmission rate is disclosedin ASTM Standard F1249. More preferably, the moisture transmission rateis about 0.01.

In one exemplary embodiment of the invention, the outer layer is madefrom metallized polyester or polypropylene material with a thickness ofapproximately 0.48 mil. The metallized polyester protects the enclosedgel 20 from environmental factors. The outer layer preferably has asmooth surface appearance that accepts customary printing. Althoughstraight foils can be used as the outer layer in the present invention,they are not preferred due to their typical crinkled and pock markedappearance which leads to poor print quality.

The intermediate layer is preferably made from polyester material with athickness of approximately 0.48 mil. The inner layer is preferably madefrom low density polyethylene material with a thickness of approximately2 mil. It is preferable to use low density polyethylene material sinceit is chemically compatible with an agarose gel. The film in thisexemplary embodiment has a moisture transmission rate of about 0.01grams at 100° F./100 square inches/24 hours.

The upper and lower sheets 12, 14 are sized to provide a cavity 18within the package 10 that allows the gel 20. As discussed above, a seal16 is formed along the edges around the package 10 to prevent airleakage. Of course, if the upper and lower sheets 12, 14 are contiguousalong one side, i.e., folded over the gel 20, only three sides need tobe sealed since the fourth side is inherently sealed. For a 6×10 cm gel,a single gel package 10 according to the present invention, is formedwith upper and lower sheets 12, 14 that have a preferred width ofapproximately 9.91 cm (3.9 inches) and a preferred length ofapproximately 13.91 cm (5.48 inches). This permits a seal to be formedaround the package having a width of preferably between about 0.635 cm(0.25 inches) and about 0.9525 cm (0.375 inches). This will leave aninside spacing of about 1 cm±2 mm all around the edges of the 6×10 cmgel 20.

To further protect the gel 20 from inadvertent bending, it may bedesirable to incorporate of one or more support sheets 24. In oneembodiment of the invention, a support sheet 24 is located under the gel20 and provides a semi-rigid backing for the gel 20. The support sheet24 preferably has a length and width at least that same as the gel 20.More preferably, the support sheet 24 has a length and width thatextends past the ends of the gel 20 as shown in FIG. 2. The addeddimensions on the support sheet 24 help to prevent damage to the edgesof the gel 20 during sealing and shipment. A sheet smaller than thedimension of the gel is not desirable. The larger the gel (e.g., 20×25cm), the more preferable it is to incorporate support sheets 24.

For example, testing has shown that for a 6×10 cm gel is best protectedwhen centered on a support sheet 6.2×10.6 cm±1 mm, and a 10×15 cm gel isbest protected when centered on a support sheet 10.2×15.6 cm±1 mm.However, it should be recognized that alternate sizes and shapes for thesupport sheet 24 are contemplated in the present invention depending onthe size and shape of the gel and the users needs.

The support sheet 24 is preferably made from high impact polystyrenematerial or oriented polystyrene material with a thickness of about 10mil. One or both surfaces of the support sheet 24 can be textured tominimize movement of the support sheet 24 within the package 10. In onepreferred embodiment, the support sheet 24 is textured on the sidefacing the package 10 and smooth on the side adjacent to the gel 20.Testing has shown that the smooth surface adheres evenly to the gel 20both when first placed onto the support sheet 24 and after over twelvehours of sitting in a sealed package 10. However, texturing of bothsides is also contemplated if desired. It should be recognized that ifadditional stiffness is desired, an additional support sheet 24 can beincorporated on top of the gel 20. Alternatively, a thicker supportsheet 24 can be used if desired.

The use of the support sheet 24 also permits the end user to easilyremove the gel 20 from the package 10 since it provides a semi-rigidsurface to grab or slide a spatula under. This is especially importantfor larger size gels 20 which would otherwise be very difficult tohandle. If desired, the support sheet 24 as described above can beinserted with the gel 20 into a gel holder that is used to conduct thetesting (not shown). Preferably the material from which the supportsheet 24 is made has a density of greater than 1.0 to prevent thesupport sheet 24 from floating if used with the gel 20 during testing.Also, depending on the process used to initially insert the gel 20 intothe package 10, the support sheet 24 can be used to facilitate suchinsertion. It is preferable that the support sheet material beultraviolet light transparent to allow the user to photograph the gel 20while on the sheet 24.

In an alternate embodiment of the invention shown in FIGS. 5 and 6A and6B, a support tray 30 is incorporated into the package 10′ to furtherstiffen the package 10′ and protect the electrophoresis gel 20. In thisembodiment, the gel 20 is preferably disposed or cast in the tray 30.The tray 30 includes a base 32 and at least two side walls 34 integrallyformed with the base 32 and spaced apart from one another to receive agel 20 therebetween. More preferably, there are four side walls 34formed around the base 32. The tray 30 is designed to prevent pinchingor crushing of the edges of the gel 20. More specifically, in a sealedpackage, the edges of the package angle toward one another at the seal.If the gel contained within such a package should migrate toward thatsealed edge during shipping, the taper of the edges could cause crushingor pinching of the edge of the gel resulting in de-watering of the gel.Gels with such deformities can produce sample irregularities during use,such as sample migration.

To prevent this occurrence, the present invention incorporates a trayinto one embodiment of the package 10′ which is designed to maintain thegel 20 at a uniform thickness until it is desired to be used. The trayalso provides additional stiffness to the package 10′ to minimizebending of the gel 20.

A preferred tray 30 for use in the present invention is slightly largerthat the gel 20 so as to provide a snug fit between the gel 20 and tray30. However, in order to accommodate dimensional variations in the gel,the tray 30 is more preferably between about 1% to 2% longer than thegel 20, between about 1% to 2% wider than the gel 20, and has side walls34 that have a height equal to (FIG. 6A) or slightly shorter than(between about 1% to about 5%) (FIG. 6B) the height of the gel 20 whenthe gel is placed within the tray 30. While the side walls 34 can beslightly taller than the height of the gel 20, doing so will reduce thecontact between the top sheet 12 of the package and the top surface ofthe gel 20 when sealed. As such, the resulting constraint that suchcontact provides is lessened. It is not desirable to make the length orwidth of the tray shorter than the gel 20 since doing so will result ingel compression and deformation of the wells.

It is also preferable that the tray 30 not include any sharp cornerswhich can damage the gel 20 or puncture the package 10′. Accordingly, inone embodiment of the invention (shown in FIGS. 6A and 6B), the package10′ includes a small flange 36 around the top of the side walls andincludes radii on all the corners. It should be recognized that thickerpackage materials could eliminate the need for radii on the edges and aflange.

The tray 30 can be formed from any suitable material. Preferably, thetray is made from a plastic material that is reasonably rigid. Therigidity of the tray 30 will vary depending on the material, tray sizeand thickness. Those skilled in the art would readily be capable ofselecting a suitable tray material for use in the present invention inlight of the teachings provided herein. In one embodiment, the traythickness (i.e., the thickness of the base and side walls) is betweenabout 0.010 inches to about 0.040 inches.

In the embodiment of the invention utilizing a tray 30, a support sheet24 is generally not needed since the tray 30, in combination with thetop and bottom sheets 12, 14, provides the necessary rigidity to preventbending of the gel, and permits the gel to be readily extracted from thepackage.

As discussed above, the tray side walls 34 are preferably designed sothat they are the same size as or slightly smaller than the gel 20(FIGS. 6A and 6B). As such, the vacuum sealing of the package 10′ causesthe top sheet 12 to apply a slight downward pressure on the top surfaceof the gel 20. The downward pressure on the gel 20 locks it into placewithin the tray, thereby inhibiting movement. The height of the sidewalls 34 prevent the pressure from the top sheet 12 from crushing thegel 20. As a result, movement of the gel 20 within the package 10 isminimized.

During development of the present invention, the inventors at firstconsidered vacuum sealing to be inappropriate since it was believed thatit would result in loss of moisture from the gel, and would cause thegel to become damaged from compression caused by the packaging. However,testing proved that the process did not cause any appreciable moistureloss and that the packaging materials conformed to the shape of the gelrather than crushing it. The addition of the tray greatly expands thecapabilities and resulting rigidity of the package.

Another benefit provided by the packaging configuration according to thepresent invention is that the increased stiffness provided by theoverlapping sheets 12, 14 allows thinner sheets to be used to form thepackage 10. This results in a packaging arrangement that is lessexpensive to manufacture. Furthermore, the thinner sheets prevent thegel 20 from being damaged during vacuum forming. For example, if thicksheets of material are used to form the package, they will resistbending when subjected to a vacuum force, more so than a thinner sheet.(The sheets bend to conform to the shape of the gel 20 when the air isevacuated from within the cavity.) Instead of bending, the thickersheets tend to compress the gel 20. The use of thinner sheets in thepresent invention allows the sheets 12, 14 to conform more readily tothe shape of the gel 20, thereby evacuating more air without damagingthe gel 20. The problems described above with respect to thicker sheetsmay also occur with materials that have relatively high stiffnesscharacteristics, such as polyethylene terephthalate (PET) material.

The incorporation of the tray into the package, on the other hand,permits thicker or stiffer sheets to be used, if desired, since the trayside walls will prevent the top sheet from compressing the gel.Alternately, since the tray adds considerable rigidity to the package,the bottom sheet may be thinner than the top sheet.

The present invention also contemplates the insertion of multiple gels20 into the package 10. Referring to FIGS. 3 and 4, an embodiment of thepackage 10 is shown containing a series of stacked gels 20. FIG. 7Ashows an alternate embodiment of the package 10′ containing a series ofstacked gels 20 within a single tray 30. FIG. 7B illustrates anembodiment of the invention wherein multiple trays, each containing anassociated gel, are stacked within the package 10′. In this embodiment,it is contemplated that locking ledges (not shown) may be formed on thebottom of the tray to secure the trays in a stack. The upper and lowersheets 12, 14 and tray of these embodiments are the same as discussedabove except that they are larger to accommodate the added number ofgels 20.

In order to prevent the gels 20 from adhering to one another, oneembodiment of the present invention contemplates the incorporation ofspacers 26 interleaved between adjacent gels 20. The spacers 26 arepreferably made from high impact polystyrene material or orientedpolystyrene material which provides a semi-rigid backing for the gel 20.The spacers 26 are preferably 10 mil thick and are textured on one sideto reduce adherence of the spacer 26 to the adjacent gel 20. Althoughthe spacer 26 can be textured on both sides, it is preferable that thespacer is smooth on one side to assist in adhering one gel (i.e., theupper gel) on the spacer 26. Testing has proven that the smooth surfaceadheres evenly to the gel 20 both when first placed onto the supportsheet 24 and after over twelve hours of sitting in a sealed package 10.

The spacers 26 preferably have a length and width at least that same asthe gel 20. More preferably, the spacers 26 each have a length and widththat extends past the ends of the gel 20, but are less than the innerdimensions of the package (FIG. 3) or tray (FIG. 7A). The addeddimensions on the spacers 26 help to prevent damage to the edges of thegel 20 during sealing and shipment. The larger the gel (e.g., 20×25 cm),the more preferable it is to incorporate spacers 26. In addition toseparating adjacent gels 20, the spacers 26 permit the gels 20 to beremoved one at a time from the package 10 since it provides a semi-rigidsurface to grab or slide a spatula under. This is especially importantfor larger size gels 20 which would otherwise be very difficult tohandle. If desired, the spacer 26 can be inserted with the gel 20 into agel holder that is used to conduct the testing (not shown). Preferablythe material from which the spacer 26 is made has a density of greaterthan 1.0 to prevent the spacer 26 from floating if used with the gel 20during testing. Also, depending on the process used to initially insertthe gel 20 into the package 10, the spacer 26 can be used to facilitatesuch insertion. It is preferable that the spacer 26 material beultraviolet light transparent to allow the user to photograph the gel 20while on the spacer 26.

If further rigidity is needed in the multi-gel embodiment, an end card(not shown) can be used on the top of the stack of gels. The end card ispreferably made from plastic material, such as polystyrene or corrugatedpolyethylene. The end card has a preferred thickness of about 15 mils ormore. In one embodiment of the invention, the end card thickness isselected from a range between about 15 mil and about 40 mil. The endcard preferably has the same dimensions as described above with respectto the spacer 26. The end card may also be necessary in the single-gelembodiment when the gels are relatively large inasmuch as such gels canbe damaged more easily from inadvertent crushing, or from contact withthe pouch materials during vacuum sealing or placement and removal ofthe gel.

In order to form the package 10, the gel 20 is preferably first placedon the bottom sheet 14, and the top sheet 12 is placed on top. For thepackage configuration 10′ that includes a tray 30, the gel is firstplaced in (or cast in) the tray 30, then the combination is placedbetween the top and bottom sheets 12, 14. The package 10, 10′ is thenplaced in an evacuation chamber, such as a Ultravac® 2000 chamber, soldby Koch Supplies, Inc., Kansas, Mo. The air is evacuated from thechamber resulting in the air between the first and second sheets 12. 14also being evacuated. Once a sufficient amount of air is evacuated so asto cause the edges of the sheets to overlie one another, the sides ofthe package 10, 10′ are sealed with a heat seal 16.

In the embodiment of the invention without a tray, a suitable package 10was produced by operating the Ultravac® 2000 chamber with the followingsettings: Vac=98; Vacplus=0; Sealing=0.9; Cooling=5/99; and Venting:pulse from 99 to 0. A vacuum of about 27 inches of mercury is used inthis embodiment of the invention, which is sufficient to evacuate apackage 10 formed from 3 mil upper and lower sheets without damaging thegel 20. During testing it was determined that a vacuum of less than 20inches of mercury was insufficient to produce a suitable package 10, butthat a vacuum of about 23 inches of mercury or more would work well. Ofcourse, a package 10 made from sheets of varying thickness may requiremore or less or a vacuum to properly evacuate the contained air andconform to the gel without causing damage. It is contemplated that othertypes of seals and method(s) of evacuating the air from within thepackage may be substituted for the disclosed method. It is alsocontemplated that other conventional vacuum sealing technique, such asgas flushing, can be used to form a package according to the presentinvention provided that the process is tailored to provide sufficientevacuation and sealing without damaging the gel.

It should be readily apparent that the process settings, such as vacuumpressure, length time of vacuum, cooling time, etc., would need to beadjusted depending on the type of vacuum chamber used, the physicalcharacteristics and material properties of the gel, and the packagingmaterial selected. The goal would be to tailor the settings so as tosufficiently evacuate the package 10 while preventing the gel from beingcrushed. Such modifications and alterations would be readily appreciatedby one skilled in the art in light of the instant disclosure.

During testing it was determined that between 1% and about 89% of theair within the package 10 without the tray should be evacuated in orderto immobilize the gel within the package 10. More preferably, betweenabout 25% and about 40% of the air within the package should be removedto provide sufficient immobilization of the gel to prevent damage. Thoseskilled in the art, however, will readily appreciate that the desiredamount air to be removed from the package will depend on the size of thegel (larger gels need more air removed because they are heavier and,therefore, are better protected when the package more closely conformsto the gel); the size of the package (a perfectly fitting package doesnot require the removal of much, if any, air); the stiffness of thepackage material (which will govern how easily the material drapes overthe gel); and whether support sheets are used in the package (supportsheets add protection, thus, lessening the amount of evacuation needed).

If the package 10′ includes a tray 30, a similar method as describedabove is carried out to form the package 10′. Between 1% and 99.9% ofthe air within the package should be evacuated in order to immobilizethe gel within the package 10. More preferably, between about 25% andabout 50% of the air within the package should be removed to restrainthe gel and tray within the package. Once again, those skilled in theart will readily appreciate that the desired amount air to be removedfrom the package will depend on the various factors described above, aswell as the stiffness and shape of the tray being incorporated into thepackage.

In order to protect the gel 20 from inadvertent damage during opening,the package 10 preferably includes indicia 28 (shown in FIG. 1) formedon the upper and/or lower sheet 12, 14 indicating where the user shouldcut to avoid contacting the gel. Preferably the indicia 28 instructs theuser to open three sides of the package 10. In an alternativeembodiment, one or more tear notches (not shown) may be formed in thepackage 10 providing the user with a easy method for tearing open thepackage 10.

The present invention provides a novel packaging configuration forprotecting an electrophoresis gel from damage during shipment andstorage. By vacuum sealing the gel within a durable pouch, the presentinvention minimizes movement of the gel that would otherwise causedamage. The incorporation of a tray into the package configurationfurther protects the gel from damage. While the above discussion hasdescribed the use of the invention with agarose gels, the presentinvention is suitable for use with all electrophoresis gels, such aspolyacrylamide and similar polymeric materials. Also, while the presentinvention has applicability to a variety of gel thicknesses, it isparticularly useful for gels between 2 mm to 7 mm thick since those gelsare especially prone to damage during shipping.

Although the invention has been described and illustrated with respectto the exemplary embodiments thereof, it should be understood by thoseskilled in the art that the foregoing and various other changes,omissions and additions may be made therein and thereto, without partingfrom the spirit and scope of the present invention.

What is claimed is:
 1. A package comprising a first sheet; a secondsheet sealed to the first sheet along at least three sides so as to forman enclosed cavity, the enclosed cavity being at least partiallyevacuated of air; and at least one electrophoresis gel disposed withinthe cavity; wherein the partially evacuated cavity contains gas having apressure between about 11% and about 99% of atmospheric pressure.
 2. Apackage according to claim 1 wherein the partially evacuated cavity gaspressure is between about 60% and about 75% of atmospheric pressure. 3.A package according to claim 1 further comprising a tray and wherein theelectrophoresis gel is located within the tray.
 4. A package accordingto claim 3 wherein the tray has four side walls formed integral with abase, each side wall having a height less than the height of theelectrophoresis gel when the electrophoresis gel is located within thetray.
 5. A package according to claim 4 wherein the height of the sidewalls is between about 1% to about 5% shorter than the height of theelectrophoresis gel when the electrophoresis gel is located within thetray.
 6. A package according to claim 4 wherein the length and width ofthe tray are each between about 1% to about 2% larger than the lengthand width of the gel.
 7. A package according to claim 4 wherein the trayhas a wall thickness between about 0.010 inches and about 0.040 inches.8. A package according to claim 3 wherein a plurality of electrophoresisgels are disposed within the tray.
 9. A package according to claim 3wherein a plurality of electrophoresis gels and trays disposed betweenthe first and second sheets, each gel being located in an associatedtray.
 10. A package according to claim 1 wherein the at least oneelectrophoresis gel is an agarose gel.
 11. A package according to claim1 further comprising a support sheet disposed between at least oneelectrophoresis gel and the first sheet.
 12. A package according toclaim 1 wherein a plurality of electrophoresis gels are disposed withinthe cavity.
 13. A package according to claim 12 wherein a spacer islocated between adjacent electrophoresis gels.
 14. A package accordingto claim 1 wherein the first sheet includes an outer layer of metallizedpolyester adhered to an inner layer of polyethylene.
 15. A packagecomprising a first sheet; a second sheet sealed to the first sheet alongat least three sides so as to form an enclosed cavity, the enclosedcavity being at least partially evacuated of air; at least oneelectrophoresis gel disposed within the cavity; and a tray; wherein theelectrophoresis gel is located within the tray; and wherein the tray hasat least two opposed side walls, the side walls having a height nolarger than the height of the electrophoresis gel when the gel islocated within the tray.
 16. An electrophoresis gel package comprising:a pouch formed from first and second sheets that are sealed to oneanother along their edges to form an enclosed cavity, the cavity beingat least partially evacuated of air; and at least one electrophoresisgel disposed within the cavity; wherein the partially evacuated cavitycontains gas having a pressure between about 11% and about 99% ofatmospheric pressure.
 17. A package according to claim 16 wherein thepartially evacuated cavity gas pressure is between about 60% and about75% of atmospheric pressure.
 18. A package according to claim 16 furthercomprising a tray and wherein the electrophoresis gel is located withinthe tray.
 19. A package according to claim 18 wherein the tray has fourside walls formed integral with a base, each side wall having a heightless than the height of the electrophoresis gel when the electrophoresisgel is located within the tray.
 20. A package according to claim 19wherein the height of the side walls is between about 1% to about 5%shorter than the height of the electrophoresis gel when theelectrophoresis gel is located within the tray.
 21. A package accordingto claim 19 wherein the length and width of the tray are each betweenabout 1% to about 2% larger than the length and width of the gel.
 22. Apackage according to claim 18 wherein the tray has a thickness betweenabout 0.010 inches and about 0.040 inches.
 23. A package according toclaim 18 wherein a plurality of electrophoresis gels are disposed withinthe tray.
 24. A package according to claim 18 wherein a plurality ofelectrophoresis gels and trays disposed between the first and secondsheets, each gel being located in an associated tray.
 25. A packageaccording to claim 16 wherein the at least one electrophoresis gel is anagarose gel.
 26. A package according to claim 16 further comprising asupport sheet disposed between at least one electrophoresis gel and thefirst sheet.
 27. A package according to claim 16 wherein a plurality ofelectrophoresis gels are disposed within the cavity.
 28. A packageaccording to claim 27 wherein a spacer is located between adjacentelectrophoresis gels.
 29. A package according to claim 16 wherein thefirst sheet includes an outer layer of metallized polyester adhered toan inner layer of polyethylene.
 30. An electrophoresis gel packagecomprising: a pouch formed from first and second sheets that are sealedto one another along their edges to form an enclosed cavity, the cavitybeing at least partially evacuated of air; at least one electrophoresisgel disposed within the cavity; and a tray; wherein the electrophoresisgel is located within the tray; and wherein the tray has at least twoopposed side walls, the side walls having a height no larger than theheight of the electrophoresis gel when the gel is located within thetray.
 31. A method of forming an evacuated package for anelectrophoresis gel comprising the steps of: providing a first sheet ofpackaging material; placing an electrophoresis gel on the first sheet;placing a second sheet of packaging material over the first sheet, theoverlying edges of the first and second sheets defining the edges of thepackage and defining a cavity for the gel; evacuating the air frombetween the first and second sheets without damaging the electrophoresisgel; and sealing the edges of the package so as to enclose the geltherein; wherein the air between the first and second sheets isevacuated so as to form a package upon sealing containing air at apressure between about 11% and about 99% of atmospheric pressure.
 32. Amethod of forming an evacuated package according to claim 31 wherein theelectrophoresis gel is located within a tray, the tray being positionedbetween the first and second sheets.
 33. A method of forming anevacuated package according to claim 31 wherein the air between thefirst and second sheets is evacuated so as to form a package uponsealing containing air at a pressure between about 60% and about 75% ofatmospheric pressure.